U.S. Pat. No. 5,574,981 teaches a method and a device for supervising the condition of a receiving antenna by transmitting a measuring signal through a first measuring path, transmitting the same measuring signal to the antenna, directing the signal produced from the energy reflected by the antenna through a second measuring path, and comparing the magnitude or energy level of both signals to determine whether the antenna is faulty, thereby taking into consideration the properties of components shared by both paths over the period of transmission.